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Guys, whats a better lube/oil for the rear diff......

2K views 5 replies 6 participants last post by  BKH 
#1 · (Edited)
There's been alot of negative talk about the brand known as RED LINE. As we know, many members are happy with ROYAL PURPLE's products. So when changing the fluid in the M5 sedan's rear diff. should one use Royal Purple or Red Line??? Is the one better than the other for this SPECIFIC application? The reason why Im asking is because Im about ready to change my Dinan 3.45 rear diff. fluid, since I now have put a bit over 1000 miles on the rear diff. The auto shop that I use will more than likely dump fresh Red Line rear diff. lube oil into the Dinan rear diff., since they used the Red Line product when installing the Dinan rear diff.
Should I tell them I'd rather have the Royal Purple product instead???
Thanks for your replies.
Robert :confused2
 
#3 ·
robert,

I would say go with the royal purple. I know that somem people are not crazy about their motor oils in m5's and hence some like the redline better in the engine but since royal purple seems to be the "lube" of chioce here on the board, try that.

Im not a large fan of castrol, even though they do have a partnership with BMW. Im a mobil guy through and through....you may want to check them out as well, just as kirkland suggested.
 
#4 ·
This string contiunes to amaze me. There is a large amount of previous information that would cast a doubt on the wizdom of changing from the factory OEM lubricants to either RP or Redline, both in the engine, transmission and rear end differential. Can someone enlighten me as to the benefit of such a move. More HP, greater TBO's or another racer edge? I cannot imagine any of these coming into play unless one were involved in serious racing where the machinery is torn down frequently between races so as to mitigate long term issues. I am sure it's no coincidence that both Reline and RP sponser numerous race cars and perhaps there are team efforts as well. None of this translates to our typical M5 driver experience unless of course you are a big budget race team. For most of us the underlying warranty is a much heavier burden than any possible micro benefit (if any), that could come from changing out OEM lubricants prior to the warranty lapse.

Having asked the question I must admit to being overly anal about oil and lubrication fluid changes. I have maintained a religious practice of changing my OEM engine oil at no more then 1500 miles ouich . Probably way out of line for the driving I do but it gives me a certain piece of mind.

As noted in a previous post I had installed Redline in a 2002 540I that I traded in for my 2003 M5. Tried to located the new owner to no avail so as to suggest that he switch back to the OEM lubrications. Time will tell how his transmission holds up. Interestingly though, I bought the Redline from the local BMW dealer and they had no qualms about puting it in the gear box. Go figure that one?

Spooky 1
2003 Imola Red
 
#5 ·
Spooky 1 said:
This string contiunes to amaze me. There is a large amount of previous information that would cast a doubt on the wizdom of changing from the factory OEM lubricants to either RP or Redline, both in the engine, transmission and rear end differential. Can someone enlighten me as to the benefit of such a move. More HP, greater TBO's or another racer edge? I cannot imagine any of these coming into play unless one were involved in serious racing where the machinery is torn down frequently between races so as to mitigate long term issues. I am sure it's no coincidence that both Reline and RP sponser numerous race cars and perhaps there are team efforts as well. None of this translates to our typical M5 driver experience unless of course you are a big budget race team. For most of us the underlying warranty is a much heavier burden than any possible micro benefit (if any), that could come from changing out OEM lubricants prior to the warranty lapse.

Having asked the question I must admit to being overly anal about oil and lubrication fluid changes. I have maintained a religious practice of changing my OEM engine oil at no more then 1500 miles ouich . Probably way out of line for the driving I do but it gives me a certain piece of mind.

As noted in a previous post I had installed Redline in a 2002 540I that I traded in for my 2003 M5. Tried to located the new owner to no avail so as to suggest that he switch back to the OEM lubrications. Time will tell how his transmission holds up. Interestingly though, I bought the Redline from the local BMW dealer and they had no qualms about puting it in the gear box. Go figure that one?

Spooky 1
2003 Imola Red
I have used redline diff and transmission oil in a 911RS with very good results, slicker changes. Smoother and quieter. I used thinner gearbox oil that has a higher effective EP rating. Red line were very helpful and a lot of track boxes use these sophisticated oils. Porsche use a very basic fit for purpose non synthetic gearox oil, not sure what the standard M5 oil is. You do need to be careful of different oil for LSD's some will reduce the plate friction and reduce the effectiveness of the standad LSD's. Redline are very helpful on advising the right oils for the job. I used a mix for the geabox from memory ;)

The car felt sharper and quicker but that could of been subjective
 
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